Furnace



E. LUNDGREN May 2s, 1929.

FURNACE Filed July 2, 1923 2 Sheets-Sheet llllf/ A TTORNE K5 May 2s, 1929. E, LUNDG'REN Y 1,715,139

FURNACE Filed July 2, 1925 2 Sheets-Sheet 2 O O O O O O O 4 O O Nvv v v 20 32 .34 204g 46 3 if/000,5???

INVENTOR 50M/V wma/Ffm ATTORNEYS Patented May 28, 1929.

' UNITED fsrArEs vEDWIN LUNGREN, or FREDERICK, MARYLAND, Ass'IGNoRYro' co n Y NEERING CORPORATION, or yNEW YORK, N; yima'ootroritzrroiv-013iNEWY I FURNACE. f,

Application med July 2, 1923. serial Nfefiaesv.; l

My invention relates to furnaces, and has special reference to furnaces of the underfeed stoker type. t

An object of the invention is to provide a novel and improved furnace of this type.

Another object of the invention is to provide a dumping grate structure for a furnace having novel and improved means for supplying a cooling agent to the parts of the structure that are exposed to the heat of the furnace.

Another object of the invention is to provide a dumping grate structure in which the air that is utilized in other parts of the stoker to assist combustion may also be utilized as a cooling agent for said parts of the structure.

Another object of the invention is to provide a dumping grate structure in which a supply of air is utilized as a cooling agent therefor, and a separate supply of air is uti lized to cool the refuse of the fuel supported by the structure and to insure the complete combustion of any unconsumed fuel in the refuse.

With these and other objects in view, the features of the invention consist in certain constructions, arrangements and combinations of parts hereinafter described and claimed, the advantages of which will be obvious to those skilled in the art.

The several features of the invention will be clearly understood from the following description and accompanying drawings, in which,-

Figure 1 is a longitudinal sectional view, partly in elevation, of part of an underfeed Stoker embodyin the features of the invention in their pre erred form;

Fig. 2 is a sectional plan View, taken substantially on the line 2-2 of Fig. 1;

F ig. 3 is a sectional view, partly in elevation, taken on the line 3-3 of Fig. 1; and

Fig. 4 is a detail sectional view taken on the line 4-4 of Fig. 1.

The underfeed stoker illustrated in the drawings is provided with a plurality of downwardly and rearwardly inclined retorts '2 having side walls 4, bottom walls 6, and tuyre blocks 8 spanning the margins of adjacent side walls of the retorts. The stoker is further provided with a'bridge wall 10, and an ash pit 12 located between the rear en d of the retorts and tuyre blocks and the bridge transmitan,

wall. A wind box 1st-having is located beneath theretorts `and tuyre blocks for supplying airthereto.kr

.Ertei- As shown the stokcr'is providedvwith y of oppositely disposed dump vgrates 18and, which are arranged pend, to end: ,withf-.theilr outer ends-mountedfon rock shaftsj22 andv l24,

respectively, so as to enable thedumplgrates to be swung into and out of closed position. 'lhe rock shaft 22 issquare incrosssection and extends through bearing sleeves 26 zwhich are removably mountedfon rocking movement in bearingsk in brackets Y2,8 projecting from a supporting beam30 extendingv across the rear ends of the retorts. ,Therock-,shaft 24 is square in cross. section and extends through squared aperturesyi-n bearing'fsle'eves 32 that are removably mounted-in bearingsiin f brackets 34 projecting from an. `I-beam l3G which serves as a lsupportl for the .bridge Wall 10. Both of the dump lgrates ,18' and 20 are made in a plurality of sections each havinga frame 38 which is made; up ofabottom wall 40 and an end wall 42. Each section of the grate 18 is mounted between adjacent brackets 28, and each section ofthe grateQO is mounted between acljacentz-brackcts 34. Each section of the grates 418and `:ZOis 'provided with a pluralityofbars44 -that extend longitudinally of the frame 38 andare arranged side by sidewith'their innerends y abutting the end walls 42 of the frame. The bars 44 are H-shaped in cross section and are provided with downwardly opening Slots 46 to enable the bars to be slipped over the rock shafts of the grates. Thev adjacent vertical walls of the bars 44 are spaced apart by means of spacing plates 47 and 49'at their' ends, re- Y f spectively, so as to provide a lspace 48 be'- tween them. Each grate section isy further provided with a cover member 50 which *tits over the top edges of the bars, andthe cover,

frame 38 and bars are' tsecured together by means of bolts 52. The bottom .wall40 tof each frame and the cover 50 are each provided with a plurality of elongatedslots VS4-which register with the spaces 48 between the bars so that openings are provided-that'extend completely' throughthe grates. IThese openings in the grates`1'8 andl 20 enable air to pass from the ash pit to the refuse'ofv the fuel supported by the grates so as to msure the complete combustion of any un'consumed' fuel.

Y ing curved surfaces.

Air is supplied to the ash pit beneath the grates through an air supply conduit 55 leading throtigh the forward wall of the ash pit and controlled by a damper 57 therein.

The inner end ofthe horizontal or web portion of each of the bars is spaced a distance from the end wall L12, so that each bar co-operates with the bottom wall 40 and the cover 50 to provide an air passage having inlet and outlet openings 56 and 58 in the outer end of the grate section and located beneath and above 'the plane of the web of the bar, respectively.

The inlet and outlet openings 56 and 58 of the air passages of each section of the grate 1S register with the rear ends of air passages 61 and 62. respectively, that extend between adjacent brackets 28. These air passages 61 and 62 are formed by a wall 64 which is a division wall between the two passages, a bottom wall 66 for the passage 61, and a top wall 68 for the passage 62. The walls 6l, 66 and 68 extend between adjacent brackets 28 and are integral with the brackets and with the beam 30. The forward portions of the outer surfaces of the bottom 40 and the cover 50 of each section of the grate 18 are curved concentricall-v with the axis of the rock-shaft 22; the inner surfaces of the rear ends of the walls 66 and 68 are correspondingly curved: and the adjacent end surfaces of the webs of the bars l1 and the division wall 6l are also correspondingly curved so as to permit limited rocking movement of the grate 18 without disturbing the substantiallj7 air tight joint formed by said engag- The top and bottom walls 6l and 66 of each of the air passages 61 extend rearwardlyv between adjacent side walls of the retorts to outlet openings 69 leading from an air chamber 7 0. This air chamber 70 is provided with an angle-shaped wall 72 mounted on the bottom wall 16 of the wind box and extending between the side walls of the furnace, and air under pressure is supplied to the chamber through a conduit 7l extending through an aperture in the wall 16 and controlled by a damper 76. The air passages 62 open into the spaces beneath the bottom walls and between the side walls of the retorts and thus into the wind box of the furnace.

With this construction it will be apparent, upon air being admitted to the air chamber 70 that it will pass through the air passages 61 through the inlet openings 56, then through the several air passages in each section of the grate beneath the webs of the grate bars. then forwardly over these webs, and then through the passages 62 and the spaces beneath the bottom walls 0f the retorts to the wind box. Thus the air from the air chamber 70 is circulated through each section of the grate 18 in a plurality of separate currents so as to cool the grate, and then in a more or less heated condition passes into the wind box directly beneath the retorts and tuyre structures.

The inlet openings 56 of each section of the dump grate 20 register with the forward end of an air passage 78 leading from an air ychamber 80 which 1s formed by the I-bearn 36 and a similar beam 82 spaced a distance to the rear thereof and secured together by bolts S1, the top and bottom of the air chamber being closed by plates 86 extending across the top and bottom of the beams, respectively, and the ends of the air chamber being formed by the side walls of the furnace. Air is supplied to the air chamber through a conduit 88 which is controlled by a damper 90. Each air passage 78 is formed by walls 92 and 91 that extend between and are integral with adjacent brackets 31 and are secured t0 the I-beam 36. The outlet openings 58 of each section of the grate 20 open into an air chamber or passage 96 which extends between adjacent brackets 31, and is formed by the wall 91 that constitutes a division Wall between the passage 96 and the passage 7 8, and a beam 98 extending between the side walls of the furnace. The air chambers or passages 96 lead into a space 100 in the bridge wall back of tnyere blocks 102 and 10-1 which are set into a recess in the bridge wall. The tuyre block 102 is provided with corrugations on its top and bottom surfaces which forms air passages leading from the spaces 100 into the fire box of the furnace, the blocks 102 resting upon the beam 98 and supporting the bloc s 10-1. The blocks 101 are provided with forwardly tapering tn vre openings 106. The outer surfaces of the rear end portions of the bottom wall 40 and the cover 50 of each section of the grate 20 are curved concentrically to the axis of the rock shaft 21; the inner surfaces of the forward end portion of the wall 92 and the beam 98 which engage these surfaces are correspondingly curved: and the adjacent end surfaces of the webs of the bars of each. grate section and the wall 91 are also correspondingly curved so as to permit limited rocking movement of the grate while maintaining substantially air tight joints between these enga-ging surfaces.-

With this construction it will be apparent that upon air being admitted to the air chamber 80, it will pass through the air passages in each grate section, then through the air passages 96, and then through Vthe tuyre blocks 102 and 106 to the interior of the furnace.

In my Patent No. 1,406,199, dated Feb. 14, 1922, a dump grate of hollow construction is illustrated and described in which the air after passing into the interior of the dump grate to cool the same, passes through openings in the top surface of the dump grate to the refuse of the fuel supported thereby.

With such prior constructions, however, air should not be admitted to the `dump grates when they are empty or until shortly beforeA the dumping operation and must be shut off before the start of the dumping operation, for the reason that if this air is admitted when the dump grates have been cleared of the accumulated ashes and clinkers it would materially reduce the CO2 content of the gases and decrease the combustion eiiciency. Thus with such prior constructions `the dump grates are for the greater part of the time exposed either to the radiant heat of the fuel bed or to the heat of the ashes and clinlters resting upon the same, which of course is objectionable.

In the present construction, however, the disadvantages of such prior constructions are overcome by the circulation of air at all times through the interior of the dump grates so as to maintain the dump grates at the requisite low temperature, the air passing through the dump grate 18 entering the wind box of the furnace, and the air passing through the dump grate 20 passing through the tuyre` blocks 102 and 106. The requisite air supply to the clinkers and ashes on the dump grates is effected at the proper times by the air passing through the openings in the dump grates, this air supply being controlled by the' damper 57.

The construction of the dump grates is such as to enable the parts thereof, including the bars 44, to be easily assembled and taken apart for the purposes of replacement or repair.

As will'be evident to those skilled in the art my invention permits various modifications without departing from the spirit thereof or the scope of the appended claims.

lVhat I claim is:

1. A furnace having, in combination, a fire box, fuel supporting means, an ash pit for receiving the refuse of the fuel from said fuel supporting means, a dump grate of hollow construction extending a dista-nce across the ash pit and having inlet and outlet openings, means for directing air into the dump grate through said inlet opening, and means associated with said outlet opening for directing the air into the fire box of the furnace at a point remote from the dump grate, said dump grate having a plurality of openings extending upwardly therethrough for permitting air from the ash pit below the dump grate to pass to the refuse supporting surface of the dump grate independently of the air supplied to the interior of the dump grate by said air directing means.

2. A furnace having, in combination, a fire box, fuel supporting means, an ash pit for receiving the refuse of the fuel from said fuel supporting means, a dump grate of hollow construction extending a distance across the ash pit having inlet and outlet openfaceof the dump grate independently of the14 air supplied to the' interior of the'dump grate by said air directing means, and controllable means for supplying air to the ash pit.

3. A furnace having, in combination, fuel supporting air admitting means, 'an' ash pit adjacent to the rear end thereof, a dump grate of hollow construction extending a distance across the ash pit and'having inlet and outlet openings therein, means for directing air int-o the dump grate through said inlet opening, and means associated with said outlet opening for directing the air to the fuel supporting surface of said fuel supporting air admitting means. Y

4. A furnace having, in combination, a fire box, fuel supporting means, an ash pit adjacent the rear end of the fuel vsupporting means, a dump grate of hollow construction extending a distance across the ash pit havmeans for directing air into the dumprgrate through said inlet opening, and means associated with said outlet opening` for directing the air into the fire box of the furnace.

5. A furnace having, in combination, fuel supporting means, a bridge'wall spaced from the rear end of the fuel supporting means, a tuyre structure mounted in the forward side of the bridge wall, an ash pit located between the rear end of said fuel supporting means and the bridge wall, dump grates of hollow construction extending a distance across the ash pit and arranged end to end with their outer ends adjacent to said fuel supporting means and said bridge wall, respectively, and means for circulating air through the dump grates and directing it to the fuel supporting surface of said fuel supporting means and said tuyre structures, respectively.

6. A furnace comprising a dump grate of ing inlet and outlet openings in one end,

hollow construction pivotally mounted at one end and having a plurality of air passages extending longitudinally thereof, each air passage having inlet and outlet openings in Said end of the dump grate so as to enable separate currents o air to be circulated through the interior of the grate.

7. A furnace comprising a dump grate of hollow construction pivotally mounted at one end and having a plurality of air passages extending.longitudinally thereof, each air passage having inlet and outlet openings in said end of the dump grate so as to permit separate currents of air to be circulated through the interior of the grate, said grate and outlet openings in said pivoted end of the grate.

9. A furnace having, 1n combination, fuel supporting means con'iprising a plurality of downwardly and rearwardly inclined fuel retorts arranged side by side and spaced apart with tuyre structures spanning the spaces between the margins of adjacent retorts, a

wind box beneath the retorts, an ash pit at the rear of said fuel supporting means, a dump grate extending a distance across the ash pit and having its forward end pivotally mounted and arranged at the rear end of the fuel supporting means, and having an air passage extending longitudinally thereof, said air passage having inlet and outlet openings in said end of the dump grate, and means for directing air into said inlet opening, and for discharging the air into said wind box as it leaves said outlet opening.

10. A furnace having, in combination. fuel supporting means, an ash pit at the rear thereof, a rock shaft extending across the furnace and mounted adjacent one of the walls of said ash pit, and a dump grate mounted on said rock shaft comprising a plurality of bars substantially H-shape in cross section arranged side by side and each having one of its ends secured on said rock shaft, plates extending over the top, bottom and other ends of said bars and cooperating with each of the bars to provide an air passage extending from the rock shaft end of the bar over one side of its central portion to its other end, then across the latter end of said central portion, and then over the other side of said central portion to said rock shaft end of the bar, and means for directing air under pressure into one end of said air passage and conducting the air from the other end of the air passage into the furnace.

11. A furnace having fuel supporting means, an ash pit for receiving the refuse of the fuel from the fuel supporting means, a dump grate of hollow construction extending a distance across the ash pit and through which air may pass, and means for directing air into the interior of the dump grate, said dump grate having a plurality of openings extending upwardly therethrough for permitting air from the ash pit below the dump grate to pass to the refuse supporting surface of the dump grate independently of the air supply to the interior of the dump grate .by said air directing means.

EDWIN LUNDGREN. 

